It is known that certain water soluble phthalocyanine and naphtalocyanine, mixed cyanine and metallocyanine compounds can be used as photobleaching and anti-microbial agents. Phthalocyanines and naphthalocyanines or their metal complexes can form "singlet oxygen".
Singlet oxygen can be formed by chemical as well as photochemical processes. Singlet oxygen is a highly oxidative species capable of reacting with substances, for example, with stains on a fabric to bleach them to a colorless and usually water-soluble state. There are many examples of phthalocyanines and naphthalocyanines photobleaches, the most common being the zinc and aluminum phthalocyanines. In the literature the term "photosensitizer" is often used instead of "photoactivator" and may therefore be considered as standing equally well for the latter term used throughout this specification
The prior art teaches phthalocyanine and naphthalocyanine compounds having the general structure ##STR1##
where Me is a tnansition or non-transition metal, (Sens.) is a phthalocyanine or naphthalocyanine ring which, when combined with a suitable Me unit, is capable of undergoing photosensitization of oxygen molecules, R units are substituent groups which are bonded to the photosensitization ring units (Sens.) to enhance the solubility or photochemical properties of the molecule, and Y units are substituents associated with the metal atom, for example, anions to provide electronic neutrality.
It has been a task of formulators of photobleaches to modify the properties of the (Sens.) unit of the molecule to increase the quantum efficiency and/or the water solubility. Typically this has been accomplished by substitution on the photochemical (Sens.) ring. However, substituents that improve one property may have a negative effect on the other. Consequently it has proven difficult to provide photobleaches which are water soluble and efficient.
Surprisingly, it has been found that the compounds of the present invention allow formulators to increase the photoefficiency of the singlet oxygen generators while being able to maintain the other parameters of the molecule. In addition, the solubility of the photochemical singlet oxygen generator can be modified without producing an undesired effect in the photophysics of the molecule. This ability to delineate and selectively modify the key structural elements contributing to the target properties of the molecule allows the formulator to proceed without having to rely upon a "hit and miss" stratagem.
The present invention provides a means by which an effective photosensitizer can have its efficiency increased without risking a concomitant loss of other desired properties inter alia solubility or color. This task is achieved by attaching a photon "harvester" moiety to the singlet oxygen generator. This harvester absorbs ultra violet light and transfers the energy to the photosensitizer portion of the molecule via a process known to those of skill in the art as "Foster Energy Transfer". This harvester group must be within a critical distance to facilitate this energy transfer. This energy transfer acts to increase the effective number of photons absorbed by the photosensitizer unit and, as photons are "consumed" in producing singlet oxygen, an increase therefore in singlet oxygen generation.
It is therefore an object of the present invention to provide photochemical singlet oxygen generators which serve as photobleaches and photodisinfectants and which have a higher efficiency in producing singlet oxygen. It is a further object of the present invention to provide photobleaching compositions suitable for use as laundry detergent bleaching compositions.
It is a yet further object of the present invention to provide enhanced photobleaching hard surface cleaning compositions for non-porous hard surfaces, inter alia, Formica.RTM., ceramic tile, glass, or for porous hard surfaces such as concrete or wood.
It is a still further object of the present invention is to provide a method for bleaching fabric with laundry compositions comprising the photobleaching compounds of the present invention
It is yet still a further object of the present invention is to provide a method for cleaning hard surfaces with the photobleaching compounds of the present invention.